The invention relates generally to the field of refrigeration. More specifically, the invention relates to controllers in refrigeration systems. Even more specifically, the invention relates to consolidating, for example, the power connection, control circuit wiring, relays, circuit breakers, switches and indicators of a refrigeration controller into a single unit.
Refrigeration systems are used in a variety of circumstances, including refrigerated cases in grocery stores, refrigerated warehouses, air conditioners and other similar systems. In one example of a refrigeration system, illustrated in FIG. 1, a rack controller 10 receives signals from sensors 12 distributed around the refrigeration system. The sensors may include temperature sensors, pressure sensors or any other kind of sensor that would be helpful in determining the refrigeration status of the area being refrigerated.
The rack controller 10 includes logic which analyzes the signals received from the sensors 12 along with information stored within the controller and determines whether, for example, the level of refrigeration should be increased or decreased or whether the system should be defrosted. The level of refrigeration being applied and the defrosting function are determined by whether or not an assortment of loads 14 and 16 have been actuated or activated. For example, the loads 14 and 16 may include compressor motors, refrigeration valves and defrost elements. Special switches, called contactors 18 are used to isolate the high power necessary to activate some of the loads 14, such as the compressor motors, from the rest of the system. Other loads 16 do not require such isolation. In most cases, the wiring to the loads 16 and the contactors 18 is protected by a circuit breakers (or fuses) 20. Further, power to the loads 16 and contactors 18 can be interrupted by opening switches 21.
An electronic relay board 22 controls activation of the loads 16 and the contactors 18. Typically, the electronic relayboard 22 includes one relay for every load 16 and contactor 18. The rack controller 10 controls the refrigeration system by sending commands to the electronic relay board 22 which causes one of the loads 14 and 16 to actuate or un-actuate.
The system typically includes mechanisms to allow manual control of the loads 14 and 16. For example, the system may include a set of toggle switches 24 that can be used to override the rack controller 10 and actuate or un-actuate a particular load 14 and 16. Further, the system typically includes a set of indicator lights 26, typically one or more for each load 14 and 16, which illuminate when various events or conditions concerning the loads 14 and 16 occur. For example, the system may include one light that will indicate that a load is actuated. Another light may indicate that control of the load has been overridden by actuation of one of the toggle switches.
Typically, all of the components shown in FIG. 1 are separate items that are wired and powered separately. For example, the toggle switches 24, indicators 26, and switches 21 may be on a door of a rack panel or panels separate from the electronic relay board 22. At installation, wiring between the switch/indicator rack panel and the electronic relay board 22 is installed. The circuit breakers 20 are typically installed in another panel, which is wired to the electronic relay board 22 upon installation.
The invention eliminates much of the wiring associated with a refrigeration control system by consolidating in a single module several of the functions of the control system. For example, in one embodiment, the functions of the electronic relay board, the circuit breakers, the toggle switches, the indicator lights, and the power connections for all of the circuits are consolidated into a single module.
In one aspect, the invention features a refrigeration control apparatus comprising a master unit. The master unit includes a mother board, which includes a bus configured to carry signals between boards coupled to the mother board. The master unit further includes a processor board interfaced to the mother board. The processor board comprises a processor, a program memory, and instructions for the processor stored on the program memory. An interface circuit is coupled to the mother board. A load control module is interfaced to the mother board. The load control module comprises an interface circuit coupled to the mother board. A circuit breaker is coupled to a power input. A load relay is coupled to the circuit breaker. The load relay is configured to switch power. An override switch and the processor are coupled to the load relay to control the load relay. An indicator is coupled to the processor and the override switch.
Implementations of the invention may include one or more of the following. The refrigeration control apparatus may include a slave unit coupled to the master unit. The slave unit may comprise a mother board and a load control module. The refrigeration control apparatus may further include a communications circuit coupled to the processor. The communications circuit may comprise a serial communications circuit, a network communications circuit or both. The refrigeration control apparatus may include a rack controller interfaced to the master unit through the communications circuit. The load relay may include a first interlocked relay and a second interlocked relay. Line voltage may be removed from the second interlocked relay when the first interlocked relay is actuated. The override switch may have a first position and a second position. The first interlocked relay may be actuated when the override switch is in the first position and the second interlocked relay may be actuated when the override switch is in the second position. The override switch may have a third position. The first interlocked relay and the second interlocked relay may be under the control of the processor when the override switch is in the third position. The indicator may provide a first indication when the override switch is in the first or second positions. The indicator may provide a second indication when the override switch is in the third position and the first interlocked relay is actuated. The indicator may provide a third indication when the override switch is in the third position and the second interlocked relay is actuated. The load control module may comprise a circuit interface module configured to be coupled to one or more loads. The loads may be one or more selected from the group of a coil on a refrigeration valves and a coil on a defrost contactor. The load control module may comprise a compressor module configured to be coupled to one or more loads comprising a coil on a compressor contactor.
The refrigeration control apparatus may include a fault circuit configured to detect the occurrence of a fault and report it to the processor board. The processor may be configured to illuminate a fault indicator upon the occurrence of the fault. The refrigeration control apparatus may include a fault reset switch coupled to the processor board. The processor may be configured to stop illuminating the fault indicator when the fault reset switch is activated. The refrigeration control apparatus may include a fault circuit configured to detect the occurrence of one or more of a plurality of faults and report the existence of one or more faults and the identity of the one or more faults to the processor board. The processor may be configured to report the identity of the one or more faults to a rack controller.
In general, in another aspect, the invention features a refrigeration control system comprising a rack controller, sensors coupled to the rack controller, a refrigeration control apparatus coupled to the rack controller, and one or more loads coupled to the refrigeration control apparatus.
Implementations of the invention may include one or more of the following. The coupling between the refrigeration control apparatus and the rack controller may be a network coupling or a serial communications coupling. The refrigeration control system may further comprise an electronic relay board coupled to the rack controller and one or more loads coupled to the electronic relay board. The refrigeration control system may further comprise a slave refrigeration control apparatus coupled to the refrigeration control apparatus.
In general, in another aspect, the invention features a method for controlling a plurality of loads in a refrigeration system comprising consolidating in an output control module, coupled to one or more loads via load circuits, circuit protection for the load circuits, load status indication, load control and a single power connection for the one or more loads.
Implementations of the invention may include one or more of the following. The method may include indicating, for each load, whether application of power to the load is under software control or override control. The method may further include controlling, for each load, whether the application of power to the load is under software control or override control. The method may further include interfacing the output control module to a processor interface module via a buss board. The method may further include controlling a load coupled to the output control module from the processor interface module when software control for the load is selected. The method may further include controlling the processor interface module with a multiple-processor-interface-module controller.